Fair Value Measurement - Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Financial assets:
Loans Held-for-sale, Fair Value Disclosure	$ 191	$ 1,000
Level 1
Financial assets:
Cash and cash equivalents	5,193	4,164
Restricted cash for securitization investors	400	308
Net loans held for investment	0	0
Loans Held-for-sale, Fair Value Disclosure	0	0
Interest receivable	0	0
Other investments	0	0
Financial liabilities:
Deposits with defined maturities	0	0
Securitized debt obligations	0	0
Senior and subordinated notes	0	0
Federal funds purchased and securities loaned or sold under agreements to repurchase	0	0
Interest payable	0	0
Level 2
Financial assets:
Cash and cash equivalents	25,663	17,582
Restricted cash for securitization investors	0	0
Net loans held for investment	0	0
Loans Held-for-sale, Fair Value Disclosure	11	5,091
Interest receivable	2,104	1,460
Other investments	1,326	1,344
Financial liabilities:
Deposits with defined maturities	45,531	18,062
Securitized debt obligations	16,918	15,122
Senior and subordinated notes	30,744	27,842
Federal funds purchased and securities loaned or sold under agreements to repurchase	883	820
Interest payable	527	281
Level 3
Financial assets:
Cash and cash equivalents	0	0
Restricted cash for securitization investors	0	0
Net loans held for investment	302,920	270,508
Loans Held-for-sale, Fair Value Disclosure	0	0
Interest receivable	0	0
Other investments	0	0
Financial liabilities:
Deposits with defined maturities	0	0
Securitized debt obligations	0	0
Senior and subordinated notes	0	0
Federal funds purchased and securities loaned or sold under agreements to repurchase	0	0
Interest payable	0	0
Carrying Value
Financial assets:
Cash and cash equivalents	30,856	21,746
Restricted cash for securitization investors	400	308
Net loans held for investment	299,091	265,910
Loans Held-for-sale, Fair Value Disclosure	11	4,862
Interest receivable	2,104	1,460
Other investments	1,326	1,344
Financial liabilities:
Deposits with defined maturities	45,858	17,923
Securitized debt obligations	16,973	14,994
Senior and subordinated notes	30,826	27,219
Federal funds purchased and securities loaned or sold under agreements to repurchase	883	820
Interest payable	527	281
Estimated Fair Value
Financial assets:
Cash and cash equivalents	30,856	21,746
Restricted cash for securitization investors	400	308
Net loans held for investment	302,920	270,508
Loans Held-for-sale, Fair Value Disclosure	11	5,091
Interest receivable	2,104	1,460
Other investments	1,326	1,344
Financial liabilities:
Deposits with defined maturities	45,531	18,062
Securitized debt obligations	16,918	15,122
Senior and subordinated notes	30,744	27,842
Federal funds purchased and securities loaned or sold under agreements to repurchase	883	820
Interest payable	$ 527	$ 281